The Career Development Program is designed to provide training and guidance for academic physician scientists, clinician-investigators and laboratory-based scientists who wish to dedicate their efforts to translational research in the area of diagnosis, prevention and treatment of breast cancer. In order to meet this goal, the Career Development Program has developed these specific objectives: 1. To recruit and train physicians and scientists to become outstanding translational investigators in the field of breast cancer; 2. To educate awardees in the basic principles of cancer biology, at both the molecular and cellular level, with an emphasis on translational science; 3. To provide a firm foundation for awardees in the specific area of breast cancer biology, laboratory, clinical and epidemiologic evaluation; 4. To guide awardees through the development process of becoming effective breast cancer translational researchers. We will achieve these objectives through a strong mentorship program in which awardees will be instructed in the principles of clinical and epidemiological breast cancer, combined with basic science studies of cell biology and cancer biology. The Career Development Program will recruit senior medical or laboratory-based postdoctoral fellows and junior faculty who wish to develop a career in translational research focussed on breast cancer;in addition, established senior faculty who wish to re-direct or extend their ongoing research programs will be eligible for participation.